The present invention relates to driving assistance display apparatus for displaying, on the screen, an image around a vehicle shot by a vehicle-mounted camera, and in particular to driving assistance display apparatus preferable for three-dimensionally making recognizable an image around a vehicle on a two-dimensional screen.
A rearview system for presenting an image from a wide angle camera mounted at the rear of a vehicle to a driver without correction is common as apparatus for presenting an image from a vehicle-mounted camera to a driver to assist driving. The rearview system mainly aims at assisting safety check required in backing a vehicle and parking.
FIG. 18 explains a conventional rearview system. This rearview system includes an a wide angle camera 2 mounted at the rear of a vehicle 1 and shooting the rear of the vehicle, image synthesis/conversion unit 3 for synthesizing images from the wide angle camera 2 and applying viewpoint conversion on the resulting image, and a monitor 4 for displaying an image generated by the image synthesis/conversion unit 3.
The wide angle camera 2 is mounted to shoot the rear of the vehicle 1. An image acquired by the wide angle camera 2 has undergone processing to remove lens distortion by the image synthesis/conversion unit 3 and is converted to an image as if shot from an arbitrary virtual view point and displayed on the monitor 4. The driver can check safety at the rear of the vehicle by using this image.
While a single wide angle camera 2 is shown in FIG. 18, it is possible to substitute a plurality of cameras for a wide angle camera. For example, as the system shown in the U.S. Pat. No. 5,649,331, incase images from a plurality of cameras are synthesized into a single screen, individual cameras need not necessarily wide angle cameras but a wide angle image is displayed on the monitor 4.
Apart from this, according to a conventional technology described in the Japanese Patent Publication No. 1999-338078, when a camera image from right and left camera is displayed on a blind corner monitor, the right/left screen, a monitor screen 5 as shown in FIG. 17, into two sub-screens 5a, 5b. The driver uses the images shown on the two sub-screens 5a, 5b to check the situation on the right and left sides on the vehicle as blind spots.
Further, in using a conventional rearview system for assistance of parking, as shown in a monitor screen 6 of the conventional rearview system shown in FIG. 19, a guide line 6b showing the width of the vehicle and a guide line 6c showing the distance from the rear of the vehicle are superimposed on a bumper image 6a at the rear end of the vehicle shot by a wide angle camera. The driver uses the bumper image 6a and the guide lines 6b, 6c superimposed thereon as auxiliary information to follow vehicle parking procedure.
In the aforementioned conventional rearview system, a scene such as that shown in FIG. 14, that is, when two parallel straight lines 10, 11, two drum-shaped objects 12, 13 arranged apart on the straight line 10, and a mark 14 drawn between the two drum-shaped objects 12, 13 on the straight line 10 are shot by a wide angle camera 2, a considerably curved image 10a, 11a and curved drum-shaped object images 12a, 13a and a mark image 14a on the curved image 10a are displayed, for example as shown in FIG. 15 or 16.
In this way, when an image shot by the wide angle camera 2 is displayed on the monitor screen without correction, the position and shape of the subject such as the drum-shaped objects 12, 13 and the straight lines 10, 11 are considerably distorted. The driver cannot understand the displayed image intuitively and without a sense of incongruity in all the areas of a monitor screen 7.
The plumb line of a three-dimensional object such as the drum-shaped objects 12, 13 does not coincide with the plumb line in the monitor screen 7, which is not intended to help intuitively understand the direction the three-dimensional object. For example, in order to simply display the position of a three-dimensional object, the inclination of the plumb line of the drum-shaped object 12, 13 shown in FIG. 15 is preferably used to indicate the bearing. This results in that the plumb line of a three-dimensional object does not coincide with the plumb line of the screen but is displayed at an angle.
In the example of FIG. 15, the drum-shaped objects 12, 13 are shown as if installed on the surface of a sphere. Displaying the plumb line of a three-dimensional object such as the drum-shaped objects 12, 13 so that the plumb line will coincide with the plumb line of the screen results in the camera bearing totally different from the intuitive bearing thus making it difficult to find the position of the three-dimensional object.
In the example shown in FIG. 16, the right angle direction gradually converges as both ends of the screen 7 is approached. Thus the positions of the drum-shaped objects 12, 13 are different from the real positions at the rear of a vehicle and the drives sees the straight lines 10, 11 as if they were curves 10a, 11a extending diagonally backward from the vehicle.
In case right and left images independent from each other are displayed on the same screen, setting the right/left screen shape allows intuitive understanding of the directions of the right and left cameras as well as display of three-dimensional objects in respective images without a sense of incongruity according to the conventional art shown in FIG. 17. The conventional art in FIG. 17, however, does not solve the problem of how to display in a single screen a wide field of view such and the shooting range of a wide angle camera.
In a monitor screen 6 of a conventional rearview system to assist parking shown in FIG. 19, cameras are mounted so that the bumper at both rear ends of the vehicle and the rear area thereof are shot. The conventional rearview system displays an image shot by a wide angle camera on the monitor screen 6 without correction. This considerably bends a bumper image 6a further than the real image. Similarly, a guide line showing the vehicle width of the vehicle or a guide line 6c showing the distance from the rear end of the vehicle are displayed in curves although they are actually straight lines. This complicates the relation between the vehicle and objects around the vehicle.
The object of the invention is to provide driving assistance display apparatus for displaying on a single screen an image from a wide angle camera so that the driver can understand the image intuitively and without a sense of incongruity.
A driving assistance display apparatus that attains the aforementioned object includes image processing means for splitting a monitor screen into a plurality of sub-screens in correspondence with each inner face of a polyhedron obtained when the inside of the polyhedron is shot, performing image processing on an image from a vehicle-mounted camera as well as splitting the processed image in correspondence with the sub-screen areas and displaying the split screens in the corresponding sub-screen areas.
This provides a screen configuration that displays an image in a direction corresponding to the orientation of each face, thereby representing to the driver an image allowing intuitive understanding of an image displayed in each sub-screen without sense of incongruity.
Preferably, in the driving assistance display apparatus, the split screens corresponding to some of the inner faces of the polyhedron are not displayed on the monitor screen. This conceals unnecessary images from the driver.
Preferably, in the driving assistance display apparatus, the sub-screen areas adjacent to each other are displayed apart on the monitor screen. Or, in the driving assistance display apparatus, the split images with different display magnification are displayed so as to scale the corresponding sub-screen areas to the display magnification. This represent a more easy-to-watch image to the driver.
Preferably, in the driving assistance display apparatus, the split images respectively displayed in the adjacent sub-screen areas are continuous at the adjacent section. Or, in the driving assistance display apparatus, the split images respectively displayed in the adjacent sub-screen areas represent a single image overlapped in the adjacent section. This allows easy understanding of the relation between sub-screens and understanding of an object traveling across sub-screens in easy correspondence.
Preferably, in the driving assistance display apparatus, the shot image of the vehicle width range of the vehicle is displayed in the sub-screen area to display the image of the lower area in the travel direction of the vehicle among the sub-screen areas and that the shot images outside the vehicle width range are displayed in adjacent sub-screen areas. This facilitates determination on whether an object in question is an object in the travel direction of the vehicle or an object that the vehicle will come in contact with or collide with while the vehicle is traveling.